The CIA has thwarted a plot by al-Qaida's affiliate in Yemen to destroy a US-bound airliner using a bomb with a new design around the one-year anniversary of the killing of Osama bin Laden, according to the Associated Press.

US officials say the plot involved an "upgrade" of the underwear bomb that failed to detonate aboard a jetliner over Detroit on Christmas Day in 2009.

This new bomb was also built to be used in a passenger's underwear but contained a more refined detonation system.

The FBI is examining the latest bomb to see whether it could have passed through airport security and brought down an airplane, officials said. They said the device did not contain metal, meaning it probably could have passed through an airport metal detector. But it was not clear whether new body scanners used in many airports would have detected it.

The would-be suicide bomber, based in Yemen, had not yet picked a target or bought his plane tickets when the CIA stepped in and seized the bomb, officials said. It is not immediately clear what happened to the alleged bomber.

The operation unfolded even as the White House and department of homeland security assured the American public that they knew of no al-Qaida plots against the US around the anniversary of bin Laden's death. The AP learned about the thwarted plot last week but agreed to White House and CIA requests not to publish it immediately because the sensitive intelligence operation was still under way.

Read more:http://www.guardian.co.uk/world/2012/may/07/cia-al-qaida-bomb-plot